This invention relates to an apparatus and method for manipulation of a radioactive fluid. This invention also relates to a method of treating stenosis (blocked arteries) and preventing restenosis (re-blocking of the artery) which employs a radioactive fluid.
It is often desired to safely manipulate a radioactive fluid. For instance in oncology, it may be necessary to introduce a radioactive fluid into the body of a patient in for diagnostic or therapeutic purposes. Specifically, a radioactive fluid might be injected into the bloodstream or into a tumor. Alternatively, a radioactive fluid might be introduced into a balloon catheter in order to irradiate tumor cells or other cells.
Percutaneous transluminal angioplasty (PTA) is the general technique of dilatation of a blocked artery (both peripheral and coronary (PTCA) arteries) with mechanical means at the end of a catheter. The use of a balloon catheter in PTA is well known. The catheter is positioned with the balloon at the site of the blockage, typically with the assistance of a guide wire and a fluoroscope, and the balloon inflated at high pressure (e.g.: 6 to 20 atmospheres (0.6 to 2 MPa).
While the use of a balloon catheter in PTA is an effective technique, it is common for the affected artery to become re-blocked in a period of several (typically 3-6) months (xe2x80x9crestenosisxe2x80x9d). Restenosis is believed to occur as a result of injury to the arterial wall during the PTA procedure. One approach to treating restenosis is to repeat the PTA procedure. However, the expense of PTA and the inconvenience to the patient make this undesirable. An attempt at preventing restenosis is the use of a stent, which is a small, typically metal device that holds the artery open. Stents, however, are only partially effective in preventing restenosis.
An approach that appears to be quite promising is the use of radiation to prevent restenosis. In doses of 8 to 30 Gy, radiation has been shown to be relatively safe and effective in preventing restenosis. While the exact mechanism of action is not known, it is suspected that the radiation xe2x80x9cstunsxe2x80x9d the cells that cause restenosis, rendering them less able to re-block the artery.
Several approaches have been taken to supplying radiation to the affected site. One is the use of a solid radioactive source (such a beads) fixed in the end of a catheter. After PTA, the PTA catheter would be removed and the radioactive catheter inserted. This technique suffers from the disadvantage of making it difficult to center the radioactive source in the artery so that the artery is uniformly irradiated. Another disadvantage is that the catheter is radioactive the entire time it is in use, causing exposure issues for the patient and the medical personnel.
Another approach is to position a guide wire past the obstruction, slide a balloon catheter over the guide wire to the obstruction, inflate the balloon to perform the angioplasty, remove the guide wire, and replace it with a wire having a radioactive tip. This approach also suffers the disadvantages of difficulties centering the radiation source and the fact that the treatment wire is radioactive during the entire time it is in use, as well as problems associated with removing the guide wire, which may complicate response to a sudden collapse of the artery.
A technique that results in uniform irradiation is the use of a balloon catheter filled with a radioactive fluid, generally a liquid. This method has the advantage of ease of use, including automatic centering of the radiation. Further, since the catheter is not radioactive until after it is inserted into the patient, there is far less undesired radiation exposure for the patient and the medical personnel.
U.S. Pat. No. 5,199,939 (Dake) teaches a general method of preventing restenosis by supplying a source of radiation at the end of a catheter to the affected vessel. Dake uses radioactive pellets at the end of a catheter having variable stiffness along its length.
U.S. Pat. No. 5,195,962 (Martin; Vas-Cath Incorporated) describes a catheter with 3 non-concentric lumens, and a method of manufacturing such a catheter. The central lumen of the catheter can be used for a guide wire. This reference discloses several other multi-lumen catheters.
U.S. Pat. No. 5,207,648 (Gross; The Kendall Company) describes a catheter with 3 concentric lumens.
U.S. Pat. No. 5,226,889 (Sheiban) discloses a catheter having 2 balloons where the distal balloon is used to open an artery and the second, of larger diameter, is used to implant a stent.
U.S. Pat. No. 5,314,409 (Sarosiek; UVA Patents Foundation) teaches an esophageal perfusion catheter having two balloons and multiple lumens. Some of the lumens communicate with ports between the balloons.
U.S. Pat. No. 5,342,306 (Michael) is representative of several disclosures that show two balloons used to isolate a treatment area in an artery so that liquid can be introduced into the space between the balloons without being washed away by blood flow.
WO 96/17654 (Thornton; Omnitron International) teaches the use of a balloon catheter filled with a radioactive liquid. In one embodiment Thornton uses multiple concentric balloons to guard against leakage, etc. In another embodiment Thornton uses a main balloon and two additional balloons on either side of the main balloon to block the flow in the artery in case of rupture of the main balloon, thus preventing flow of radioactive liquid throughout the patient""s body.
WO 97/48452 (Lavie; The State of Israel, SOREQ) teaches a device for preventing restenosis with beta radiation from a Rhenium-186 or Rhenium-188. This reference employs several embodiments that place the radiation at the end of a catheter.
WO 98/46309 (Pipes; Mallinckrodt) teaches a double serial balloon in which one balloon is used to perform angioplasty and a second balloon on the same catheter is used to perform the radiation treatment.
Briefly, the invention comprises a manifold system for manipulating a radioactive fluid. The apparatus and method are particularly suitable for use with a balloon catheter and a radioactive liquid to prevent restenosis. The manifold system provides a convenient and relatively safe method of handling the radioactive fluid. The invention also comprises a method of sequentially removing a radioactive fluid from a container and introducing it into a catheter or other apparatus. The apparatus and method allow for the quick, convenient, and relatively safe radiation treatment of stenosed arteries without the drawbacks associated with many other techniques. The apparatus of the invention can also be used for other situations involving the handling of a radioactive liquid, such as the use of a balloon catheter filled with a radioactive liquid for use in tumor therapy.